Scientists are exploring ways to use white-light beams from sources such as streetlights and drones to wirelessly transmit information. Many light-converting materials based on light-emitting diodes (LEDs) or quantum dots, materials that otherwise could have been considered for this application, become hot and lose light-transmitting efficiency when irradiated intensely.
Garnet-type transparent ceramics—named for the crystal structure they share with silicate garnets—can withstand extreme laser excitation and efficiently convert that radiation to bright white light for visible-light communication.
Traditionally, these materials are made by compressing ceramic powders under extreme heat and pressure to remove imperfections that scatter light. Although the resulting materials can efficiently handle laser illumination, the process is energy intensive and difficult to scale, and it limits the shapes of the ceramic products.
Now researchers report a quasi-transparent garnet ceramic, grown directly from aluminosilicate glass, that enables robust long-range white-light communication (Matter 2026, DOI: 10.1016/j.matt.2026.102822).
But growing the ceramic from glass created a new problem.
“As the crystals started forming, the remaining glass stiffened around them, making it harder and harder for atoms to move where they need to go,” says Zhiguo Xia, a materials scientist at South China University of Technology and a corresponding author of the study. “Eventually the whole crystallization process just stalls.”
To address that problem, the researchers added calcium to loosen the glass network, giving atoms more freedom to rearrange during crystallization.
“Calcium’s large ionic radius makes it very effective at opening pathways through the aluminosilicate network,” Xia explains.
The team also used a staged crystallization process in which small crystals formed first and guided later growth, helping the material densify into a quasi-transparent garnet ceramic without developing the usual clouding defects.
“This is a very nice piece of work, especially because fully crystallizing garnet ceramics directly from glass is rarely achieved,” says Mathieu Allix, a materials chemist at the National Center for Scientific Research (CNRS), who was not involved in the work.
The resulting ceramic is about 30% harder than commercial transparent garnets and conducts heat roughly twice as well as many glass-based light converters and about 20 times as effectively as the silicone resins used in LEDs. The material retains high brightness at 150 °C and withstands roughly fivefold higher laser intensities than some glass-phosphor composites before it begins to dim.
The researchers demonstrated that despite typical ambient-light disturbances and other types of interference, the ceramic was able to reliably transmit white-light data signals over 1.2 km. That distance far exceeds the indoor ranges of many LED and quantum-dot systems.
For Allix, the real advance is that the new glass-based garnet composition should make larger ceramic samples easier to produce than is possible with previous approaches.
The ceramic’s emission leans heavily toward yellow light because it lacks a strong red component. That property limits the quality of the illumination and the transmitted signal, an issue Xia aims to address in future designs.
